从专利看键合金丝的发展

就如何提高键合金丝性能，满足微电子工业发展的需要，本文根据最新的金丝专利文献综述了高弧度，低弧度，高强度键合金丝的发展现状，介绍了微量添加元素的作用和Au-Cu-Ca，Au-稀土，Au-Ni,Au-Ag,Au-Cu,Au-Sn(In),Au-Pt(Pd)等键合金丝合金化的研究动向，指出键合金丝发展趋势是微量添加元素复合化，组成合金化，加工细线化。低成本化，研究重点是通过最佳的合金化元素设计提高金丝强度，可靠性及键合强度。     

键合金丝的合金化研究动向

根据最新的专利文献综述了高弧度、低弧度、高强度键合金丝的发展现状，介绍了微量添加元素的作用和Au—Cu—Ca、Au—Ag、Au—Ni、Au—Sn(In)、Au—Pt(Pd)等合金化键合金丝的研究动向，以及键合金丝的微量添加元素复合化、组成合金化、加工细线化、低成本化的发展趋势。     

金银合金系键合金丝

根据最新文献综述了高弧度、低弧度、高强度金银合金系键合金丝的最新进展，微量添加元素的作用和最佳合金化元素的设计。介绍了金银合金系键合金丝的合金组成及其性能作用，以及键合金丝的发展趋势。     

丝焊球用金合金丝及丝焊球的形成方法

此种金合金丝是在高纯金中添加了10-30ppmZn，Co，Mo，Cr这四种元素中的至少一种、添加了5～56ppm Be，Y，Ca，Bi，Fe这五种元素中的至少一种、添加了l-500ppm Pd，Pt，Cu，Au，Ag，Sn，In，Mn以上八种元素中的至少一种。通过微量元素的添加可以提高与IC芯片的接合强度，降低键合弧度。     

键合金丝的研究进展及应用

介绍了键合金丝的特性、种类及其适用的封装领域;微合金化高纯金丝、合金型金丝、复合型金丝和键合铜丝的研究发展概况,以及各类型键合丝在市场上所处的地位;键合金丝主要应用领域-集成电路(IC)和半导体分立器件的发展情况.分析了国内外键合金丝市场、产业状况以及该行业的发展趋势.     

稀土元素对键合金丝组织与性能的影响

研究了稀土元素Eu对金丝再结晶温度、组织、力学性能以及热影响区(HAZ)的作用.研究结果表明,添加一定量的Eu可以:①提高金丝的再结晶温度;②细化金丝的晶粒;③增加金丝的强度;④减小金丝的HAZ长度,即添加适当的稀土元素对于开发高强度低弧度键合金丝有积极作用.     

B微合金化9310钢的力学性能及回火组织研究

采用金相、SEM、TEM等实验方法,研究了回火温度对B微合金化9310钢的微观组织和力学性能的影响规律。研究表明:B微合金化9310钢的力学性能随回火温度的变化规律与传统9310钢基本一致。添加微量B元素,一方面降低了9310钢的强度,特别是在低温回火阶段(300℃),并使屈服强度峰值对应的回火温度向高温区移动100℃,另一方面显著提高9310钢的冲击韧度,使冲击功最低值对应的回火温度向低温区移动约50℃。微量B元素对9310钢的回火组织基本没有影响,但使原始奥氏体晶粒发生粗化,且奥氏体化温度越高,粗化效果越明显。和无B钢相比,B微合金化9310钢的冲击韧窝更深、更均匀,微量B元素促进回火过程中钢中碳化物的析出。     

汽车弹簧用合金钢的微合金化研究

对汽车弹簧用60Si2Mn合金钢中添加了微合金化元素Nb和V,并研究了其显微组织、力学性能、耐磨损性能和耐腐蚀性能。结果表明,添加微量合金元素Nb,尤其是复合添加微量合金元素Nb和V,可以提高60Si2Mn合金钢的力学性能、耐磨损性能和耐腐蚀性能。     

微合金化元素对纯铜热稳定性和导电性的影响

利用光学显微镜(OM)、透射电镜(TEM)和电导率测试等研究了添加微量合金化元素对4N纯铜的晶粒尺寸热稳定性和导电性的影响,分析了合金元素与基体中微量杂质元素S的相互作用。结果表明：添加微量Ti元素及微量Cr、Ni和Ag元素均可显著提高4N纯铜晶粒尺寸的热稳定性,经900℃×30 min高温处理后,Cu、Cu-Ti和Cu-Cr-Ni-Ag的晶粒尺寸分别为158.57、86.06和48.35μm,即热稳定性Cu-Cr-Ni-Ag>Cu-Ti>Cu。同时,添加微量合金化元素后纯铜的导电率仍较高,Cu、Cu-Ti和Cu-Cr-Ni-Ag导电率分别为101.87、101.64和99.98%IACS。分析认为热稳定性的提高主要与TiS相、CrS相的钉扎以及Ni和Ag固溶拖拽有关,微量Ti和Cr可与杂质S反应形成六方结构TiS相和单斜结构CrS相,且均与基体呈非共格关系,特别是CrS相较TiS相更为细小、数量更多。     

添加W对机械合金化TiAl合金显微组织和性能的影响

采用机械合金化结合粉末冶金技术制备了Ti-44．7A1-xW（at％）合金材料。采用透射电镜、扫描电镜和金相显微镜研究不同W添加量对机械合金化TiAl基合金的显微组织和高温抗氧化性能的影响，并对合金的力学性能进行测试。研究表明，通过机械合金化在TiAl基合金系统中添加微量W元素会形成新的固溶体相，这种新成分相大大提高TiAl基合金的抗弯强度σb当W添加量为1．0at％时，σb达到峰值；随后随着W含量的增加，抗弯强度降低。W元素的添加有效的制约了合金基体的内部氧化，使TiAl合金的高温抗氧化性能明显提高。     

一种半导体封装用键合金丝的研制

在开发了1种微合金配方的基础上,重点研究了真空熔炼连铸工艺,研制出1种适用于半导体分立器件和集成电路封装的高强度低弧键合金丝。结果表明:1)微合金元素得到有效添加,且分布均匀。2)铸锭组织为粗大柱状晶沿轴向分布。3)机械性能均匀稳定,Φ19μm:断裂负荷≥5cN,延伸率2%~6%;Φ15μm:断裂负荷≥3 cN,延伸率2%~6%。4)与国内外相同规格键合金丝相比,具有更高的强度和更大的熔断电流。     

微电子封装用键合金丝替代产品的研究现状

随着电子封装技术的发展,传统键合金丝在性能和价格上已经不具备优势。采用复合和改性等方法可以开发出满足要求的键合金丝替代品。总结了金包银复合键合丝、钯包铜复合键合丝、金合金键合丝和银合金键合丝共4种键合金丝替代产品的性能特点、成分配比、生产技术难点和关键点,介绍了部分典型产品,并对替代产品的发展趋势进行了展望。     

What is the future of bonding wire? Will copper entirely replace gold?

Thermosonic ball bonding is a major interconnect process in microelectronics packaging and is positioned to remain one of the key process technologies available to package designers in the near future. However, the main wire material used in fine pitch (FP) and ultra-fine pitch (UFP) ball bonding is gold and with significant increases in gold price, gold ball bonding has become a more costly process that has a considerable economic effect on the assembly of packages used in consumer electronics. An alternative wire material to gold is copper, which is much cheaper and has several technical benefits including better electrical conductivity and has been widely used in discrete and power devices with wire diameters typically larger than 30μm in diameter for many years. However, copper wire behaves quite differently than gold due to its different physical properties, some of which are beneficial and others detrimental to bonding performance. In this article, we briefly review some of the advantages and difficulties with using copper wire advanced packaging and explain why copper cannot replace gold in many applications and why gold offers significant benefits.     

Doped and low-alloyed gold bonding wires

Fine gold wires with diameters down to 15μm are used for bonding semiconductor devices. Increasing miniaturization of electronic circuits calls for smaller wire diameters. This requires the development of gold wires with increased mechanical strength and good bondability to replace thicker wire diameters without detriment to their functionality. The first gold bonding wires were pure gold, and then doped gold wires of high purity were developed because of their stabilized and improved mechanical characteristics. Nowadays and in the near future low alloyed gold wires are increasingly replacing doped gold wires. This paper gives an overview of the mechanical characteristics of doped and low-alloyed gold bonding wires and their bondability.     

金丝的力学特征对球键合的微观组织和性能的影响

用电子背散射衍射仪对具有不同力学特征金丝的微区组织进行表征,采用扫描电镜和光学显微镜观察线弧轮廓、热影响区和焊点形貌,并通过推拉力测试仪测量线弧拉力和焊球剪切力,分析金丝力学特征对球键合质量的影响。结果表明：半硬态1和半硬态2的金丝芯部保持纤维状组织,边缘晶粒为细小的等轴晶,沿径向微区组织形貌有明显差异。打火烧球后形成的热影响区长度短,球颈部的组织有明显的梯度性,键合后弧高较小。软态金丝的组织为粗大的等轴晶,沿径向分布均匀,键合拉力低,易发生滑球现象。半硬态2金丝与焊盘的结合力强,引线键合拉力高,综合键合质量优,是最适合球键合工艺的金丝。     

Relationship between microstructure homogeneity and bonding stability of ultrafine gold wire

Inhomogeneous microtexture evolution during the cold drawing process usually results in lean, sway, or sweep failure. The <111> longitudinal fiber texture has higher stiffness than the <100> texture and its proportion and distribution in the cross-section are critical for the bonding stability of fine gold wire. We investigated the inhomogeneous microtexture evolution of gold wire that was cold drawn through an asymmetric diamond die. In this study, the distributions of the <111> and <100> textures in a 20 μm diameter fine gold wire are the variables and their effects on the bonding stability of the wire were estimated by electron backscattered diffraction (EBSD) and finite element method (FEM) simulations. The use of a focused ion beam apparatus enabled a high quality of band contrast of the EBSD to be achieved in the exact half cross-sectional area of the fine gold wire. The detailed three-dimensional FEM results show that the asymmetric distribution of the textures plays a crucial role in increasing the spatial displacement of the gold bonding wire.     

引线键合中材料参数对硅基板应力状态的影响

利用＂热—力—超声＂增量耦合有限元模型,对采用不同引线（金,铜）以及采用铜引线在不同银镀层厚度（48,1,6μm）条件下的键合过程进行了模拟.结果表明,在其它条件不变的情况下,金引线键合过程对硅基板内应力状态的影响远小于铜引线,且应力集中的位置更接近键合中心;随着镀层厚度的增加,基板所受到的压应力逐渐减小,但基板所受到的最大压应力在硅的抗压力范围之内;同时基板所受到的剪应力也逐渐减小,由于剪应力是硅基板损坏的决定性因素,因此采用厚度为16μm的镀层对减小基板损坏更有利.     

电子行业用高纯金溅射靶材研究综述

围绕半导体集成电路产业的需求,综述高纯金提纯中杂质元素的控制,制备工艺中的金靶材结构设计、微结构调控技术及靶材与背板焊接绑定等技术的研究现状。提出通过行业协调修订相关产品标准,结合溅射设备完善靶材的结构设计,开展靶材微结构调控进行金薄膜与靶材结构的关联性研究,拓展高纯金靶材的绑定技术等研究方向。     

New Type Gold Bonding Wire

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Properties of welded joints made of Weldox 1100 steel

This study evaluated both the joint strength of copper wire on a copper substrate with tin plating and the joint reliability of copper wire bonding after heat treatment. The suitable tin thickness and bonding conditions, which are stage temperature, wire bonding power and bonding time, were chosen by the peel test after copper wire bonding. Tin thickness of 10 m showed a high bonding rate under the conditions of stage temperature 373 K, bonding power 500–700 mW and bonding time 30 50 ms. Before heat treatment, the peel strength of the copper wire on the copper substrate with tin plating conditions was weaker than that of gold wire on a gold substrate. After heat treatment for more than 70 h at 298 K, the peel strength of the copper wire became higher than that of the gold wire and twice as high as the initial bonding strength. The tin layer remained between the copper wire and copper substrate before heat treatment. When the samples were held at 298 K, tin reacted with copper and turned into a Cu–Sn intermetallic compound. Upon completion of this reaction at 298 K for over 70 h, the soft tin layer between the copper wire and copper substrate disappeared. Therefore, the peel strength of copper wire after heat treatment increased. These results were observed by scanning electron microscope images of the interface between the copper wire and copper substrate before and after heat treatment.